<?php
Class DB {

  private $link_id;
  private $handle;
  private $is_log;
  private $time;

  //构造函数
  public function __construct() {
    $this->time = $this->microtime_float();
    require_once("config.php");
    $this->connect($db_config["hostname"], $db_config["username"], $db_config["password"], $db_config["database"], $db_config["pconnect"]);
    $this->is_log = $db_config["log"];
    if($this->is_log){
      $handle = fopen($db_config["logfilepath"]."dblog.txt", "a+");
      $this->handle=$handle;
    }
  }
  
  //数据库连接
  public function connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect = 0,$charset='utf8') {
    if( $pconnect==0 ) {
      $this->link_id = @mysql_connect($dbhost, $dbuser, $dbpw, true);
      if(!$this->link_id){
        $this->halt("数据库连接失败");
      }
    } else {
      $this->link_id = @mysql_pconnect($dbhost, $dbuser, $dbpw);
      if(!$this->link_id){
        $this->halt("数据库持久连接失败");
      }
    }
    if(!@mysql_select_db($dbname,$this->link_id)) {
      $this->halt('数据库选择失败');
    }
    @mysql_query("set names ".$charset);
  }
  
  //查询 
  public function query($sql) {
    $this->write_log("查询 ".$sql);
    $query = mysql_query($sql,$this->link_id);
    if(!$query) $this->halt('Query Error: ' . $sql);
    return $query;
  }
  
  //获取一条记录（MYSQL_ASSOC，MYSQL_NUM，MYSQL_BOTH）
  public function get_one($sql,$result_type = MYSQL_ASSOC) {
    $query = $this->query($sql);
    $rt =& mysql_fetch_array($query,$result_type);
    $this->write_log("获取一条记录 ".$sql);
    return $rt;
  }

  //获取全部记录
  public function get_all($sql,$result_type = MYSQL_ASSOC) {
    $query = $this->query($sql);
    $i = 0;
    $rt = array();
    while($row =& mysql_fetch_array($query,$result_type)) {
      $rt[$i]=$row;
      $i++;
    }
    $this->write_log("获取全部记录 ".$sql);
    return $rt;
  }
  
  //插入
  public function insert($table,$dataArray) {
    $field = "";
    $value = "";
    if( !is_array($dataArray) || count($dataArray)<=0) {
      $this->halt('没有要插入的数据');
      return false;
    }
    while(list($key,$val)=each($dataArray)) {
      $field .="$key,";
      $value .="'$val',";
    }
    $field = substr( $field,0,-1);
    $value = substr( $value,0,-1);
    $sql = "insert into $table($field) values($value)";
    $this->write_log("插入 ".$sql);
    if(!$this->query($sql)) return false;
    return true;
  }

  //更新
  public function update( $table,$dataArray,$condition="") {
    if( !is_array($dataArray) || count($dataArray)<=0) {
      $this->halt('没有要更新的数据');
      return false;
    }
    $value = "";
    while( list($key,$val) = each($dataArray))
      $value .= "$key = '$val',";
    $value .= substr( $value,0,-1);
    $sql = "update $table set $value where 1=1 and $condition";
    $this->write_log("更新 ".$sql);
    if(!$this->query($sql)) return false;
    return true;
  }

  //删除
  public function delete( $table,$condition="") {
    if( empty($condition) ) {
      $this->halt('没有设置删除的条件');
      return false;
    }
    $sql = "delete from $table where 1=1 and $condition";
    $this->write_log("删除 ".$sql);
    if(!$this->query($sql)) return false;
    return true;
  }

  //返回结果集
  public function fetch_array($query, $result_type = MYSQL_ASSOC){
    $this->write_log("返回结果集");
    return mysql_fetch_array($query, $result_type);
  }

  //获取记录条数
  public function num_rows($results) {
    if(!is_bool($results)) {
      $num = mysql_num_rows($results);
      $this->write_log("获取的记录条数为".$num);
      return $num;
    } else {
      return 0;
    }
  }

  //释放结果集
  public function free_result() {
    $void = func_get_args();
    foreach($void as $query) {
      if(is_resource($query) && get_resource_type($query) === 'mysql result') {
        return mysql_free_result($query);
      }
    }
    $this->write_log("释放结果集");
  }

  //获取最后插入的id
  public function insert_id() {
    $id = mysql_insert_id($this->link_id);
    $this->write_log("最后插入的id为".$id);
    return $id;
  }

  //关闭数据库连接
  protected function close() {
    $this->write_log("已关闭数据库连接");
    return @mysql_close($this->link_id);
  }

  //错误提示
  private function halt($msg='') {
    $msg .= "\r\n".mysql_error();
    $this->write_log($msg);
    die($msg);
  }

  //析构函数
  public function __destruct() {
    $this->free_result();
    $use_time = ($this-> microtime_float())-($this->time);
    $this->write_log("完成整个查询任务,所用时间为".$use_time);
    if($this->is_log){
      fclose($this->handle);
    }
  }
  
  //写入日志文件
  public function write_log($msg=''){
    if($this->is_log){
      $text = date("Y-m-d H:i:s")." ".$msg."\r\n";
      fwrite($this->handle,$text);
    }
  }
  
  //获取毫秒数
  public function microtime_float() {
    list($usec, $sec) = explode(" ", microtime());
    return ((float)$usec + (float)$sec);
  }
}
